Looking at buying a 96 2.5 with low mileage (85K) but it's been running with a bad O2 sensor for about two years now. Should I be worried? The owner says it idles smooth and gets good mileage but I'm concerned if this could have damaged the engine in any way. Thanks in advance for any info!

 

Before the catalyst O2 or after the catalyst O2? If its before the catalyst then you are probably looking at a bad catalyst.

 

Not sure yet. Hoping not the one before cause I know a cat can be pricey. I just didn't know if a bad sensor would cause the engine to foul up from running too rich/lean.

 

I don't think it can "hurt" the engine. Once its fixed it should be fine. Especially if it runs nice already.